DESCRIPTION: (Applicant's abstract) Sources of commercially available dyes that fluoresce in the long visible/near infrared (NIR) spectrum between 650-900nm, containing a variety of reactive chemical handles are severely limited and available dyes and prohibitively expensive for many research establishments. This project seeks to introduce a new class of long wavelength/ near infrared (NIR) fluorescent dyes. Important applications of these compounds include fluorescence polarization (FP) assays and techniques, near infrared optical imaging of animal tissue, conventional fluorescence and enzymatic fluorescence assays. Initially, a combinatorial chemistry array of 27 compounds will be synthesized on a small scale (100-200ug) characterized by HPLC and Mass Spectrometry, and tested for their fluorescence and polarization properties and chemical / photostability. A smaller number of the most promising candidates (3-5) will then be synthesized on a larger scale (20-50mg) to allow for chemical activation of the probes (e.g. by the introduction of an amine-reactive N-hydroxysuccinimidyl ester handle) and for full structural characterization including NMR and elemental analysis studies. Two or three selected compounds will then be tested in a model fluorescence polarization haloperidol immunoassay. The best compound(s) will then be fitted with a variety of chemical handles for covalent attachment to various functional groups. PROPOSED COMMERCIAL APPLICATION: There is a real shortage of long-wavelength / near infrared fluorescent dyes in the 700-900nm region with chemically reactive handles commercially available at the present time despite large increasing demands for such compounds. This new class of long wavelength / near infrared dyes will be designed to bridge this gap in the market. The dyes will have good chemical and photostability, excellent fluorescence properties and water solubility, and low non-specific binding to proteinacious material and nucleic acids.